Antenna Tuning

ABSTRACT

Disclosed are various embodiments for tuning an antenna. Multiple phase sets for a tuning circuit impedance are generated. Each phase set includes multiple phase values. A reflected voltage corresponding to each of the phase values is determined. For each phase set, one of the phase values is selected based on the corresponding reflected voltage. The phase values for each phase set that is subsequent to an initial phase set are generated. The phase values are based on the selected phase value for the previous the phase set.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to copending U.S. provisionalapplication entitled “CELLULAR BASEBAND PROCESSING” assigned Ser. No.61/618,049, filed Mar. 30, 2012, the entirety of which is herebyincorporated by reference herein.

BACKGROUND

In a wireless communication device, maximum power transfer between atransceiver and an antenna may occur when the impedance of thetransceiver and the impedance of the antenna match. However, variousfactors may cause the impedance of the antenna to vary. For example,environmental conditions, the way a user holds the communication device,and other factors, may cause the impedance of the antenna to drift.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present disclosure can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the disclosure. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a drawing of a communication device according to variousembodiments of the present disclosure.

FIG. 2 is a drawing of an equivalent circuit of tuning circuitry of thecommunication device in FIG. 1 according to various embodiments of thepresent disclosure.

FIGS. 3A-3C are drawings of Smith charts illustrating examples offunctionality implemented in the communication device of FIG. 1according to various embodiments of the present disclosure.

FIG. 4 is a flowchart illustrating an example of functionality executedin the communication device of FIG. 1 according to various embodimentsof the present disclosure.

DETAILED DESCRIPTION

The present disclosure is directed towards systems, apparatus, andmethods for tuning an antenna in a communication device. A non-limitingexample is as follows. Tuning circuitry for an antenna is configured tohave a tuning impedance with a reflection coefficient having a magnitudethat is based on a predetermined impedance for a transceiver. A pair ofphase values for a first phase set for the impedance of the tuningcircuitry is generated. A reflected voltage is obtained with the tuningcircuitry using the first phase value of the phase set. A reflectedvoltage is then obtained with the tuning circuitry using the secondphase value of the phase set. The reflected voltages are compared, andthe phase value corresponding to the smallest reflected voltage isselected. A pair of phase values for a second phase set is thengenerated based on the selected phase value of the first phase set.

The process of generating pairs of phase values for phase sets based onthe selected phase value of the previous phase set may be repeated for apredetermined number of iterations. Using the selected tuning impedanceand the final selected phase value determined from the iterations, thetuning circuitry is then configured to cause the impedance of an outputpath to closely match the impedance of the transceiver. In the followingdiscussion, a general description of the system and its components isprovided, followed by a discussion of the operation of the same.

With reference to FIG. 1, shown is a drawing of a communication device103 according to various embodiments of the present disclosure. Thecommunication device 103 may be configured to transmit data to andreceive data from a base station or another communication device 103. Tothis end, the communication device 103 may comprise, for example, aprocessor-based system such as a mobile computing device or other typeof device. Such a mobile computing device may be embodied in the form ofa cellular telephone, a web pad, a tablet computer system, a laptopcomputer, a netbook, an electronic book reader, a music player, aportable gaming device, two-way radio, or any other device with likecapability.

The communication device 103 may include transceiver circuitry 106,baseband circuitry 108, tuning circuitry 109, detector circuitry 113, anantenna 116, and other components not discussed in detail herein forsimplicity. The communication device 103 shown in FIG. 1 is merely oneexample among others in accordance with the present disclosure.

The transceiver circuitry 106 may be configured to output or receive adata signal 119, such as voice data, messaging data, control data, orany other type of data, that is to be transmitted or received using theantenna 116. To this end, the transceiver circuitry 106 may include atransmitter, a receiver, processing circuitry, control circuitry, and/orother components. In order to transmit and/or receive the data signal119, the transceiver circuitry 106 may include mixers, modulators,demodulators, preamps, power amps, control circuitry, and/or othercomponents not shown for simplicity.

The baseband circuitry 108 may control various aspects of thetransceiver circuitry 106, tuning circuitry 109, and possibly othercomponents of the communication device 103. To this end, the basebandcircuitry 108 may provide a tuning control signal 123 and receive adetection signal 115, which will be discussed later. The tuning controlsignal 123 may be provided to the tuning circuitry 109 and controlvarious values and configurations of the tuning circuitry 109, whichwill also be discussed later.

Also, there may be a source impedance 129 associated with thetransceiver circuitry 106. The source impedance 129 may be complex(i.e., includes a real and imaginary component) and thereby have amagnitude and phase value. The value of the source impedance 129 may bepredetermined. For example, the value of the source impedance 129 may beset during design of the communication device 103.

The antenna 116 may receive the data signal 119 and transmit the data toa receiving device as a wireless signal. Alternatively, the antenna 116may receive a wireless signal from a transmitting device and provide thedata signal 119 to the transceiver circuitry 106. Additionally, anantenna impedance 133 may be associated with the antenna 116. Theantenna impedance 133 may be complex (i.e., have a real component andimaginary component), and thus have a magnitude and phase value.

The tuning circuitry 109 may be configured to improve the power transferbetween the transceiver circuitry 106 and the antenna 116. To this end,an adjustable tuning impedance 136 may be associated with the tuningcircuitry 109. The tuning impedance 136 may be adjusted, for example, byaltering the values of capacitors, inductors, or other types ofcomponents of the tuning circuitry 109 using the tuning control signal123.

By altering the tuning impedance 136, a load impedance 139 (asexperienced by the transceiver circuitry 106) may be adjusted. Maximumpower transfer between the transceiver circuitry 106 and the antenna 116may occur when the load impedance 139 matches the source impedance 129.As such, the tuning circuitry 109 may be configured to adjust its tuningimpedance 136 so that the load impedance 139 substantially matches thesource impedance 129. As a result, an improved power transfer andvoltage standing wave ratio (VSWR) may be obtained.

The detector circuitry 113 may be configured to detect a forward voltage(i.e., the voltage of an incident wave from the transceiver circuitry106) and a reflected voltage (i.e., the voltage reflected due to animpedance mismatch). To this end, the detector circuitry 113 may includeone or more directional couplers, bidirectional couplers, envelopedetectors, etc. The result of the detected forward voltage and orreflected voltage may be provided to the transceiver circuitry 106 usingthe detector signal 115.

Next, a general description of the operation of the various componentsof the communication device 103 is provided. To begin, it is assumedthat the communication device 103 is powered up and prepared to initiatethe procedure of matching the load impedance 139 to the source impedance129.

The communication device 103 may first determine a ratio of thereflected voltage to the forward voltage for the antenna 116. To thisend, the detector circuitry 113 may obtain and measure the reflectedvoltage and the forward voltage. With the reflected voltage and theforward voltage obtained, the communication device 103 may determine theratio thereof.

The communication device 103 may then select a magnitude for areflection coefficient of the tuning impedance 136. The selectedmagnitude for the reflection coefficient of the tuning impedance 136 maybe based on a predetermined impedance of the transceiver circuitry 106.For example, the selected magnitude for the reflection coefficient ofthe tuning impedance 136 may be slightly greater than the magnitude ofthe transceiver circuitry 106.

Additionally, the magnitude for the reflection coefficient of the tuningimpedance 136 may be based on the ratio of the reflected voltage to theforward voltage for the antenna 116. For example, the selected magnitudemay be proportional to the ratio of the reflected voltage to the forwardvoltage. Thus, if the ratio of the reflected voltage to the forwardvoltage were relatively high, the selected magnitude for the reflectioncoefficient of the tuning impedance 136 may be relatively high ascompared to when the ratio is relatively low.

With the magnitude for the reflection coefficient of the tuningimpedance 136 being selected, the communication device 103 may begin theprocess of determining the phase value of the tuning circuitry 109 sothat the load impedance 139 may closely match the source impedance 129.The communication device 103 may generate a first phase set, wherein thefirst phase set includes multiple phase values. For example, thecommunication device 103 may generate a first phase set that has a pairof phase values. The phase values of the first phase set may bepredefined in various embodiments. Thus, as a non-limiting example, thefirst phase set may include a first phase value of π radians and asecond phase value of 0 radians.

The tuning circuitry 109 may then be configured to have the previouslyselected magnitude for the reflection coefficient of the tuningimpedance 136. Additionally, the phase of the tuning impedance 136 maybe selected to be the first phase value of the first phase set. Usingthis configuration, the communication device 103 may transmit or receivea data signal 119 and determine the reflected voltage using the detectorcircuitry 113.

The tuning circuitry 109 may then be configured so that the tuningimpedance 136 has a phase that is the second phase value of the firstphase set. Again, the communication device 103 may transmit or receive adata signal 119 and determine the reflected voltage using the detectorcircuitry 113.

The two reflected voltages may be compared, and the phase value of thefirst phase set that corresponds to the smaller reflected voltage may beselected. Using the selected phase value from the first phase set, thecommunication device 103 may then generate the phase values for thesecond phase set. As a non-limiting example, the first phase value ofthe second phase set may be the selected phase value from the firstphase set plus π/4 radians. Also as a non-limiting example, the secondphase value of the second phase set may be the selected phase value fromthe first phase set minus π/4 radians.

Using the first phase value of the second phase set, the communicationdevice 103 may determine the corresponding reflected voltage. Then, thecommunication device 103 may determine the reflected voltage thatcorresponds to the second phase value of the second phase set. Thesereflected voltages may be compared, and the phase value that correspondsto the smallest reflected voltage may be used to determine the phasevalues of the third phase set.

The process of generating phase values for subsequent phase sets may berepeated over multiple iterations. As a non-limiting example, thefollowing equation may be used to determine the first phase value foreach phase set that is subsequent to the first phase set:

$\begin{matrix}{{\theta_{1\; k} = {\theta_{k - 1} + \frac{\pi}{2^{k}}}},} & \left( {{eq}.\mspace{14mu} 1} \right)\end{matrix}$

wherein k is the iteration number, θ_(1k) is the first phase value forthe k^(th) phase set, and θ_(k−1) is the selected phase value from theimmediately previous phase set (i.e., the phase value from theimmediately previous phase set that corresponds to the smaller reflectedvoltage).

Additionally, the following, equation may be used to determine thesecond phase value for each phase set that is subsequent to the firstphase set:

$\begin{matrix}{{\theta_{1\; k} = {\theta_{k - 1} - \frac{\pi}{2^{k}}}},} & \left( {{eq}.\mspace{14mu} 2} \right)\end{matrix}$

wherein k is the iteration number, θ_(2k) is the second phase value forthe k^(th) phase set, and θ_(k−1) is the selected phase value from theimmediately previous phase set (i.e., the phase value from theimmediately previous phase set that has corresponds to the smallerreflected voltage).

From eqs. 1-2, it may be appreciated that the difference between thefirst phase value and second phase value decreases for each subsequentphase set. As such, the process described above may be stopped after thecompletion of a predetermined number of iterations. Thus, with referenceto eqs. 1-2, the process may be stopped upon k reaching a predeterminedvalue. As an alternative, the process may be stopped upon the reflectedvoltage being within a predetermined threshold.

Upon the iterations being stopped, the phase value of the final phaseset that corresponds to the smallest reflected voltage may be selectedand stored. The stored phase value may be used to configure the tuningcircuitry 109 so that the load impedance 139 closely matches the sourceimpedance 129, as will now be described.

With reference now to FIG. 2, shown is an equivalent circuit of thetuning circuitry 109 of FIG. 1 according to various embodiments. Asshown, the equivalent circuit of the tuning circuitry 109 includes afirst admittance 203, a second admittance 206, and a third admittance209. Additionally, a load reflection coefficient 213 is represented. Theload reflection coefficient may be a ratio of the forward voltage to thereflected voltage.

The tuning circuitry 109 may be modeled as both a lossless and areciprocal two-port network. A lossless network has the followingcharacteristics:

$\begin{matrix}{\left. {{\sum\limits_{k = 1}^{n}\; {S_{ki}S_{kj}^{*}}} = \begin{matrix}1 & {{{for}\mspace{14mu} i} = j} \\0 & {{{for}\mspace{14mu} i} \neq j}\end{matrix}} \right\},} & \left( {{eq}.\mspace{14mu} 3} \right)\end{matrix}$

wherein S_(ij) represents the scattering parameter (i.e., S-parameter)of the i^(th) row and j^(th) column of a scattering matrix (i.e.,S-matrix) for the network. A reciprocal network has the followingcharacteristics:

S_(ij)=S_(ji)   (eq. 4).

Thus, from eqs. 3-4, the following relationships may be obtained for atwo-port network:

|S ₁₁ |=|S ₂₂|  (eq. 5), and

θ₂₂=π+2θ₂₁−θ₁₁   (eq. 6),

wherein θ_(ij) is a respective phase value for the network. Therefore,the scattering matrix for a lossless and reciprocal two-port network maybe expressed as:

$\begin{matrix}{S = {\begin{bmatrix}s_{11} & {\sqrt{1 - {s_{11}}^{2}}^{{j\theta}_{21}}} \\{\sqrt{1 - {s_{11}}^{2}}^{{j\theta}_{21}}} & {{- s_{11}^{*}}^{{j2\theta}_{21}}}\end{bmatrix} = {\quad{\begin{bmatrix}{{- s_{22}^{*}}^{{j2\theta}_{21}}} & {\sqrt{1 - {s_{22}}^{2}}^{{j\theta}_{21}}} \\{\sqrt{1 - {s_{22}}^{2}}^{{j\theta}_{21}}} & s_{22}\end{bmatrix}.}}}} & \left( {{eq}.\mspace{14mu} 7} \right)\end{matrix}$

Also, in a two-port network, the following relationship is present:

S* ₂₂=Γ_(L)   (eq. 8),

wherein Γ_(L) represents the load reflection coefficient 213 for thenetwork. Thus, using eq. 7, the following relationship may be obtained:

$\begin{matrix}{{S = \begin{bmatrix}{{- \Gamma_{L}}^{{j2\theta}_{21}}} & {\sqrt{1 - {\Gamma_{L}}^{2}}^{{j\theta}_{21}}} \\{\sqrt{1 - {\Gamma_{L}}^{2}}^{{j\theta}_{21}}} & \Gamma_{L}^{*}\end{bmatrix}},} & \left( {{eq}.\mspace{14mu} 9} \right)\end{matrix}$

wherein Γ_(L) is the load reflection coefficient 213, and θ₂₁ is thephase shift of the network.

Thus, upon the values of Γ_(L) and θ₂₁ being determined, the tuningcircuitry 109 may be configured so that the load impedance 139 (FIG. 1)substantially matches the source impedance 129 (FIG. 1). Γ_(L), the loadreflection coefficient 213 for the network, is the ratio of thereflected voltage to the forward voltage, which may be determined aspreviously discussed. θ₂₁ may be closely approximated by using the phasevalue of the final phase set that has the smallest reflected voltage, aspreviously discussed.

Eq. 9 may also be expressed in terms of transmission parameters (i.e.,ABCD-parameters) as follows:

$\begin{matrix}{{A = \frac{{\left( {1 + S_{11}} \right)*\left( {1 - S_{22}} \right)} + {S_{12}*S_{21}}}{2*S_{21}}},} & \left( {{eq}.\mspace{14mu} 10} \right) \\{{B = \frac{{\left( {1 + S_{11}} \right)*\left( {1 + S_{22}} \right)} - {S_{12}*S_{21}}}{2*S_{21}}},{and}} & \left( {{eq}.\mspace{14mu} 11} \right) \\{D = \frac{{\left( {1 - S_{11}} \right)*\left( {1 + S_{22}} \right)} + {S_{12}*S_{21}}}{2*S_{21}}} & \left( {{eq}.\mspace{14mu} 12} \right)\end{matrix}$

Using eqs. 10-12, eq. 9 may also be expressed in terms of admittanceparameters (i.e., Y-parameters) as follows:

$\begin{matrix}{{Y_{1} = \frac{D - 1}{B}},} & \left( {{eq}.\mspace{14mu} 13} \right) \\{{Y_{2} = \frac{1}{B}},{and}} & \left( {{eq}.\mspace{14mu} 14} \right) \\{{Y_{3} = \frac{A - 1}{B}},} & \left( {{eq}.\mspace{14mu} 14} \right)\end{matrix}$

wherein Y₁ is the first admittance 203, Y₂ is the second admittance 206,and Y₃ is the third admittance 209. Accordingly, the values for thefirst admittance 203, the second admittance 206, and the thirdadmittance 209 of the equivalent circuit of the tuning circuitry 109 maybe determined, and the tuning circuitry 109 may be configured so thatthe load impedance 139 closely matches the source impedance 129. Assuch, power transfer between the transceiver circuitry 106 and theantenna 116 may be improved.

Referring next to FIGS. 3A-3C, shown is a sequence of Smith charts 300illustrating examples of functionality implemented in the communicationdevice 103 (FIG. 1) according to various embodiments of the presentdisclosure. The Smith charts of FIGS. 3A-3C are merely examples of thevarious functionality that may be performed in the communication device103.

Beginning with FIG. 3A, the Smith chart 300 shown represents an exampleof the relationships between the source impedance 129 (FIG. 1), loadimpedance 139 (FIG. 1), tuning impedance 136 (FIG. 1), and antennaimpedance 133 (FIG. 1) upon the first phase set being generated inaccordance with the present disclosure. Point 303 represents the sourceimpedance 129, which may be known or predetermined. In the exampleshown, the transceiver impedance may be 50Ω, for example. Point 306represents the antenna impedance 133.

The points 309 a and 309 a′ represent the tuning impedances 136 of thefirst phase set. The points 309 a and 309 a′ correspond to tuningimpedances 136 using the first phase value and the second phase value,respectively, of the first phase set. The magnitude for the reflectioncoefficient of the tuning impedances 136 are based on the sourceimpedance 129, which is represented by point 303. In the example shown,the magnitudes for the reflection coefficient of the tuning impedances136 are slightly greater than the transceiver impedance. Thus, visually,the points 309 a and 309 a′ (representing the tuning impedances 136)extend outwardly with respect to the point 303 (representing the sourceimpedance 129).

In the example shown, the first phase value of the first phase set(represented by point 309 a) has a phase value of π radians, while thesecond phase value of the first phase set (represented by point 309 a′)has a phase value of 0 radians. The points 313 a and 313 a′ representthe load impedances 139 that correspond to the first phase value andsecond phase value, respectively, of the first phase set.

The communication device 103 has determined that the reflected voltagethat corresponds to the first phase value of the first phase set(represented by point 309 a) is smaller than the reflected voltage thatcorresponds to the second phase value of the first phase set(represented by point 309 a′). Thus, point 309 a (shown as darkened inthe Smith chart 300) is selected by the communication device.

Turning now to FIG. 3B, shown is a Smith chart 300 representing anexample of the relationships between the source impedance 129 (FIG. 1),load impedance 139 (FIG. 1), tuning impedance 136 (FIG. 1), and antennaimpedance 133 (FIG. 1) upon the second phase set being generated inaccordance with the present disclosure. Point 303 represents the sourceimpedance 129, and point 306 represents the antenna impedance 133. Thepoints 309 a and 309 a′, discussed previously with respect to FIG. 3A,represent the tuning impedances 136 using the phase values for the firstphase set. Further, the points 313 a and 313 b′, discussed previouslywith respect to FIG. 3A, represent the load impedances 139 thatcorrespond to the tuning impedances 136 using the phase values of thefirst phase set.

The points 309 b and 309 b′ represent the tuning impedances 136 of thesecond phase set. The points 309 b and 309 b′ correspond to the tuningimpedances using the first phase value and the second phase value,respectively of the second phase set. The phase values of the secondphase set are based on the phase value of the first phase set thatresulted in the smaller reflected voltage.

In the present example, eqs. 1-2 are being used to determine the phasevalues. Thus, in the present example, the first phase value of thesecond phase set is 5π/4 radians, and the second phase value of thesecond phase set is 3π/4 radians. The points 313 b and 313 b′ representthe load impedances 139 that correspond to the first phase value andsecond phase value, respectively, of the second phase set.

In the present example, the communication device 103 has determined thatthe reflected voltage that corresponds to the first phase value of thesecond phase set (represented by point 309 b) is smaller than thereflected voltage that corresponds to the second phase value of thesecond phase set (represented by point 309 b′). Thus, point 309 b (shownas darkened in the Smith chart 300) is selected by the communicationdevice 103.

With reference now to FIG. 3C, shown is a Smith chart 300 representingan example of the relationships between the source impedance 129 (FIG.1), load impedance 139 (FIG. 1), tuning impedance 136 (FIG. 1), andantenna impedance 133 (FIG. 1) upon the third phase set being generatedin accordance with the present disclosure. As compared to the Smithchart 300 in FIG. 3B, the Smith chart 300 in FIG. 3A now includes points309 c and 309 c′, which correspond to the tuning impedances 136 usingthe first phase value and second phase value, respectively, of the thirdphase set. Using eqs. 1-2, in the present example, the phase valuecorresponding to point 309 c is 11π/8 radians, and the phase valuecorresponding to point 309 c′ is 9π/8 radians. The points 313 c and 313c′ represent the load impedances 139 that correspond to the first phasevalue and second phase value, respectively, of the third phase set.Because the magnitude for the reflection coefficient of the tuningimpedances 136 has been selected to be slightly greater than the sourceimpedance 129 (represented by the point 303), the tuning impedance 136may trace an outline of at least a portion of a circle that surroundsthe point 303.

In the present example, the communication device 103 has determined thatthe reflected voltage that corresponds to the second phase value of thethird phase set (represented by point 309 c′) is smaller than thereflected voltage that corresponds to the first phase value of thesecond phase set (represented by point 309 c). Thus, point 309 c′ (shownas darkened in the Smith chart 300) is selected by the communicationdevice 103.

Referring next to FIG. 4, shown is a flowchart that provides one exampleof the operation of the communication device 103 according to variousembodiments. The flowchart of FIG. 4 provides merely an example of themany different types of functional arrangements that may be employed toimplement the operation of the communication device 103 as describedherein. The flowchart of FIG. 4 may be viewed as depicting an example ofsteps of a method implemented in the communication device 103 accordingto one or more embodiments.

Beginning with block 400, the communication device 103 beginstransmitting or receiving the data signal 119 (FIG. 1). In variousembodiments, the signal 119 may be transmitted or received throughoutthe process described herein. In block 403, the communication device 103obtains the reflected voltage and forward voltage from the antenna 116(FIG. 1), for example, by using the detector circuitry 113 (FIG. 1).Next, as shown in block 406, the communication device 103 determines theratio of the reflected voltage to the forward voltage, which isrepresented as Γ_(L) in eq. 9. In block 409, the magnitude of thereflection coefficient for the tuning impedance 136 (FIG. 1) of thetuning circuitry 109 (FIG. 1) is selected. The magnitude may beselected, for example, based on the predetermined source impedance 129(FIG. 1) (e.g., the transmitter and/or receiver). Additionally, themagnitude may be proportional to the ratio of the reflected voltage tothe forward voltage (determined in block 403).

Moving to block 413, the phase values for the first phase set for thetuning impedance 136 of the tuning circuitry 109 are determined. Thephase values of the first phase set may be predetermined in variousembodiments. Next, as shown in block 416, the tuning impedance 136 ofthe tuning circuitry 109 is configured to be the selected magnitude(selected in block 409) and the first phase value of the phase set.Thereafter, the reflected voltage is detected and stored, as depicted inblock 419.

The communication device 103 then moves to block 423 and configures thetuning impedance 136 of the tuning circuitry 109 to be the selectedmagnitude (selected in block 406) and the second phase value of thephase set. As shown in block 426, the reflected voltage is detected andstored. Thus, the communication device 103 determines a reflectedvoltage in response to using each of the phase values of the phase setfor the tuning impedance 136 of the tuning circuitry 109.

The communication device 103 then selects the phase value of the currentphase set that corresponds to the smaller reflected voltage (detected inblocks 419 and 426), as shown in block 429. In block 436, thecommunication device determines whether it is done generating phasesets. The process of generating phase sets may be done, for example,upon a completion of a predetermined number of iterations of generatingthe phase values. In various embodiments, the process of generatingphase sets may be done, for example, upon a reflected voltage beingwithin a predetermined threshold.

If the process of generating phase sets is not done, the phase valuesfor the next phase set is generated, as shown in block 439. Thus, aplurality of phase sets for the tuning impedance 136 of the tuningcircuitry 109 are generated. The phase values for the subsequent phaseset may be based on the selected phase value of the previous phase set.Thereafter, the communication device 103 returns to block 416, and theprocess is repeated as shown. Upon the process of generating the phasesets being done, the communication device 103 moves to block 443 andconfigures the tuning circuitry 109 so that the load impedance 139substantially matches the source impedance 129.

The flowchart of FIG. 4 shows the functionality and operation ofportions of the communication device 103. If portions are embodied insoftware, each block may represent a module, segment, or portion of codethat comprises program instructions to implement the specified logicalfunction(s). The program instructions may be embodied in the form ofsource code that comprises human-readable statements written in aprogramming language or machine code that comprises numericalinstructions recognizable by a suitable execution system such as aprocessor in the communication device 103. The machine code may beconverted from the source code, etc. If embodied in hardware, each blockmay represent a circuit or a number of interconnected circuits toimplement the specified logical function(s).

Although the flowchart of FIG. 4 shows a specific order of execution, itis understood that the order of execution may differ from that which isdepicted. For example, the order of execution of two or more blocks maybe varied relative to the order shown. Also, two or more blocks shown insuccession in FIG. 4 may be executed concurrently or with partialconcurrence. Further, in some embodiments, one or more of the blocksshown in FIG. 4 may be skipped or omitted. In addition, any number ofcounters, state variables, warning semaphores, or messages might beadded to the logical flow described herein, for purposes of enhancedutility, accounting, performance measurement, or providingtroubleshooting aids, etc. It is understood that all such variations arewithin the scope of the present disclosure.

Various systems described herein may be embodied in general-purposehardware, dedicated hardware, software, or a combination thereof. Ifembodied in hardware, each block in FIG. 4 can be implemented as acircuit or state machine that employs any one of or a combination of anumber of technologies. These technologies may include, but are notlimited to, discrete logic circuits having logic gates for implementingvarious logic functions upon an application of one or more data signals,application specific integrated circuits (ASICs) having appropriatelogic gates, one or more programmable logic devices (e.g., a fieldprogrammable gate array (FPGA), a complex programmable logic device(CPLD), etc.), or other components, etc. Such technologies are generallywell known by those skilled in the art and, consequently, are notdescribed in detail herein.

It is emphasized that the above-described embodiments of the presentdisclosure are merely possible examples of implementations set forth fora clear understanding of the principles of the disclosure. Manyvariations and modifications may be made to the above-describedembodiment(s) without departing substantially from the spirit andprinciples of the disclosure. All such modifications and variations areintended to be included herein within the scope of this disclosure andprotected by the following claims.

Therefore, at least the following is claimed:
 1. A system, comprising: atransmitter; an antenna in communication with the transmitter; andtuning circuitry for the antenna, the tuning circuitry being configuredto: generate a plurality of phase sets for an impedance of the tuningcircuitry, each of the phase sets comprising a plurality of phasevalues; select one of the phase values for each of the phase sets, theselected one of the phase values being based on a reflected voltagecorresponding to each of the phase values; and generate the phase valuesfor each of the phase sets subsequent to an initial one of the phasesets, the phase values being based on the selected one of the phasevalues of a previous one of the phase sets.
 2. The system of claim 1,wherein the tuning circuitry is further configured to select a magnitudeof a reflection coefficient for the impedance of the tuning circuitrybased on a predetermined source impedance of the transmitter.
 3. Thesystem of claim 2, wherein the magnitude of the reflection coefficientfor the impedance is further selected based on a ratio of the reflectedvoltage to a forward voltage for the antenna.
 4. The system of claim 1,wherein the previous one of the phase sets is an immediately previousone of the phase sets.
 5. The system of claim 1, wherein a differencebetween the phase values for each of the phase sets decreases for eachsubsequent one of the phase sets.
 6. The system of claim 1, wherein thetuning circuitry is further configured to configure a load impedance forthe transmitter to substantially match a source impedance upon thereflected voltage being within a predetermined threshold, the loadimpedance comprising the impedance of the tuning circuitry and anantenna impedance, the load impedance being based on a final one of theselected one of the phase values.
 7. The system of claim 1, wherein thetuning circuitry is further configured to configure a load impedance forthe transmitter to substantially match a source impedance upon apredetermined number of the phase sets being generated, the loadimpedance comprising the impedance of the tuning circuitry and anantenna impedance, the load impedance being based on a final one of theselected one of the phase values.
 8. An apparatus, comprising: circuitryconfigured to select a magnitude of a reflection coefficient for animpedance of a tuning circuit for an antenna; circuitry configured togenerate a plurality of phase sets for the impedance of the tuningcircuit, each of the phase sets comprising a plurality of phase values;circuitry configured to determine a reflected voltage in response tousing the magnitude of the reflection coefficient and the phase valuesof each of the phase sets for the impedance of the tuning circuit;circuitry configured to select, for each of the phase sets, one of thephase values based on the corresponding reflected voltage; and circuitryconfigured to generate the phase values for each of the phase setssubsequent to an initial one of the phase sets, the phase values beingbased on the selected one of the phase values of a previous one of thephase sets.
 9. The apparatus of claim 8, wherein the previous one of thephase sets is an immediately previous one of the phase sets.
 10. Theapparatus of claim 8, wherein a difference between the phase values foreach of the phase sets decreases for each subsequent one of the phasesets.
 11. The apparatus of claim 8, further comprising circuitryconfigured to configure a load impedance to substantially match a sourceimpedance upon the reflected voltage being within a predeterminedthreshold, the load impedance comprising the impedance of the tuningcircuit and an antenna impedance, the load impedance being based on afinal one of the selected one of the phase values.
 12. The apparatus ofclaim 8, further comprising circuitry configured to configure a loadimpedance to substantially match a source impedance upon a predeterminednumber of the phase sets being generated, the load impedance comprisingthe impedance of the tuning circuit and an antenna impedance, the loadimpedance being based on a final one of the selected one of the phasevalues.
 13. The apparatus of claim 8, wherein the magnitude of thereflection coefficient for the impedance of the tuning circuit is basedon a predetermined source impedance.
 14. The apparatus of claim 13,wherein the magnitude of the reflection coefficient for the impedance ofthe tuning circuit is further based on a ratio of the reflected voltageto a forward voltage for the antenna.
 15. A method, comprising:generating, in a circuit, a plurality of phase sets for an impedance ofa tuning circuit for an antenna, each phase set comprising a pluralityof phase values; determining, in the circuit, a reflected voltage inresponse to using each of the phase values of each of the phase sets forthe impedance of the tuning circuit; selecting, in the circuit, for eachof the phase sets, one of the phase values based on the correspondingreflected voltage; and generating, in the circuit, the phase values foreach of the phase sets subsequent to an initial one of the phase sets,the phase values being based on the selected one of the phase values ofa previous one of the phase sets.
 16. The method of claim 15, wherein adifference between the phase values for each of the phase sets decreasesfor each subsequent one of the phase sets.
 17. The method of claim 15,wherein generating the phase values for each of the phase sets isstopped in response to the reflected voltage being within apredetermined threshold.
 18. The method of claim 15, wherein generatingthe phase values is stopped upon a completion of a predetermined numberof a plurality of iterations of generating the phase values
 19. Themethod of claim 15, further comprising selecting, in the circuit, amagnitude of a reflection coefficient for the impedance of the tuningcircuit based on a predetermined source impedance.
 20. The method ofclaim 19, wherein the magnitude of the reflection coefficient for theimpedance is further based on a ratio of the reflected voltage to aforward voltage for the antenna.